1. Field of the Invention
The present invention relates to improvements in and relating to braking control apparatus for vehicles such as automotive vehicles.
2. Description of the Prior Art
It is troublesome for the driver of a vehicle to operate the hand brake or continuously depress the brake pedal to facilitate the driving operation of the vehicle when starting on a slope, prevent his vehicle at rest from colliding into the preceding vehicle from behind causing a double collision when his vehicle is collided from behind, prevent the vehicle from being moved forward due to a creeping phenomenon of the vehicle equipped with a torque converter and so on. As a means of overcoming these difficulties, a braking control apparatus has been proposed in the art in which once the brake pedal of a running vehicle has been depressed thus braking and bringing the vehicle to a stop, the brake pedal is locked in the depressed position by the energization of an electromagnet so that the depression of the brake pedal is maintained and thus the brakes continue to hold until the accelerator pedal is next depressed. While the conventional apparatus of this type has great advantages, it is disadvantageous in that when it is desired to depress further the brake pedal held in the previously depressed position by the electromagnet so as to apply the brakes harder, it is essential to depress the brake pedal against the electromagnetic force of the electromagnet thus requiring a considerably large amount of brake-pedal pressure.
Another disadvantage in practical use is that if the driver who overestimates the braking action of this apparatus steps out of the vehicle without applying the hand brake, there is the possibility of a situation arising in which when any fault occurs in the electric system so that the energizing current to the electromagnet is interrupted or reduced, the braking of the vehicle is partially lost thus causing an unforeseen accident.
Still another disadvantage is that when a fault occurs in the electronic or electric circuitry of the apparatus so that it can no longer perform the function of rendering the electromagnet inoperative during the time that the vehicle is in motion, the brake pedal will be locked in the depressed position by the electromagnet even when the vehicle is moving with the result that particularly when the brake pedal is depressed fully to rapidly brake the vehicle, even if the foot is lifted off the brake pedal, the rapid braking of the vehicle is maintained and thus the wheels remain locked giving rise to a very dangerous situation.